给定一个二进制数组arr[] ,任务是计算0 s 和1 s 计数相等的子数组的数量,并将所有0 s 和1 s 连续放置在该子数组中。
例子:
Input: arr[] = {1, 0, 1, 1}
Output: 2
Explanation: The subarrays satisfying the given conditions are {1, 0} and {0, 1}. Therefore, the count of such subarrays is 2.
Input: arr[] = {1, 1, 0, 0, 1, 0}
Output: 4
Explanation: The subarrays satisfying the given conditions are {1, 1, 0, 0}, {1, 0}, {0, 1}, {1, 0}. Therefore, the count of such subarrays is 4.
朴素的方法:最简单的方法是遍历给定的数组,对于每对不相等的相邻元素,迭代当前索引的左右,并检查1和0的计数是否相等。增加子数组的计数,直到发现为假。完成数组遍历后,打印子数组的总数。
下面是上述方法的实现:
C++
// C++ program for the above approach
#include
using namespace std;
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
void countSubarrays(int A[], int N)
{
// Stores the count of subarrays
int ans = 0;
for (int i = 0; i < N - 1; i++) {
// If current element is different
// from the next array element
if (A[i] != A[i + 1]) {
// Increment count
ans++;
// Count the frequency of
// 1s and 0s
for (int j = i - 1, k = i + 2;
j >= 0 && k < N
&& A[j] == A[i]
&& A[k] == A[i + 1];
j--, k++) {
// Increment count
ans++;
}
}
}
// Print the final count
cout << ans << "\n";
}
// Driver Code
int main()
{
int A[] = { 1, 1, 0, 0, 1, 0 };
int N = sizeof(A) / sizeof(A[0]);
// Function Call
countSubarrays(A, N);
return 0;
}
Java
// Java program for the above approach
import java.util.*;
class GFG
{
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
static void countSubarrays(int A[], int N)
{
// Stores the count of subarrays
int ans = 0;
for (int i = 0; i < N - 1; i++)
{
// If current element is different
// from the next array element
if (A[i] != A[i + 1])
{
// Increment count
ans++;
// Count the frequency of
// 1s and 0s
for (int j = i - 1, k = i + 2;
j >= 0 && k < N
&& A[j] == A[i]
&& A[k] == A[i + 1];
j--, k++)
{
// Increment count
ans++;
}
}
}
// Print the final count
System.out.print(ans+ "\n");
}
// Driver Code
public static void main(String[] args)
{
int A[] = { 1, 1, 0, 0, 1, 0 };
int N = A.length;
// Function Call
countSubarrays(A, N);
}
}
// This code is contributed by shikhasingrajput
Python3
# Python3 program for the above approach
# Function to count subarrays
# having equal count of 0s and 1s
# with all 0s and all 1s grouped together
def countSubarrays(A, N) :
# Stores the count of subarrays
ans = 0;
for i in range(N - 1) :
# If current element is different
# from the next array element
if (A[i] != A[i + 1]) :
# Increment count
ans += 1;
# Count the frequency of
# 1s and 0s
j = i - 1; k = i + 2;
while (j >= 0 and k < N and A[j] == A[i] and A[k] == A[i + 1]) :
# Increment count
ans += 1;
j -= 1;
k += 1;
# Print the final count
print(ans);
# Driver Code
if __name__ == "__main__" :
A = [ 1, 1, 0, 0, 1, 0 ];
N = len(A);
# Function Call
countSubarrays(A, N);
# This code is contributed by AnkitRai01
C#
// C# program for the above approach
using System;
class GFG{
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
static void countSubarrays(int[] A, int N)
{
// Stores the count of subarrays
int ans = 0;
for(int i = 0; i < N - 1; i++)
{
// If current element is different
// from the next array element
if (A[i] != A[i + 1])
{
// Increment count
ans++;
// Count the frequency of
// 1s and 0s
for(int j = i - 1, k = i + 2;
j >= 0 && k < N &&
A[j] == A[i] &&
A[k] == A[i + 1];
j--, k++)
{
// Increment count
ans++;
}
}
}
// Print the final count
Console.Write(ans + "\n");
}
// Driver Code
public static void Main()
{
int[] A = { 1, 1, 0, 0, 1, 0 };
int N = A.Length;
// Function Call
countSubarrays(A, N);
}
}
// This code is contributed by sanjoy_62
Javascript
C++
// C++ program for the above approach
#include
using namespace std;
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
void countSubarrays(int A[], int N)
{
// Stores the count
int res = 0;
// Initialize cur with first element
int curr = A[0];
vector cnt = {1};
for (int c = 1; c < N; c++)
{
// If the next element is same
// as the current element
if (A == curr)
// Increment count
cnt[cnt.size() - 1]++;
else
// Update curr
curr = A;
cnt.push_back(1);
}
// Iterate over the array count
for (int i = 1; i < cnt.size(); i++)
{
// Consider the minimum
res += min(cnt[i - 1], cnt[i]);
}
cout << (res - 1);
}
// Driver code
int main()
{
// Given arr[]
int A[] = { 1, 1, 0, 0, 1, 0 };
int N = sizeof(A) / sizeof(A[0]);
// Function Call
countSubarrays(A, N);
return 0;
}
// This code is contributed by divyesh072019
Java
import java.util.Vector;
// Java program for the above approach
class GFG {
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
static void countSubarrays(int[] A)
{
// Stores the count
int res = 0;
// Initialize cur with first element
int curr = A[0];
int[] cnt = new int[A.length];
cnt[0] = 1;
for (int c = 1; c < A.length; c++) {
// If the next element is same
// as the current element
if (A == curr)
// Increment count
cnt++;
else
// Update curr
curr = A;
cnt = 1;
}
// Iterate over the array count
for (int i = 1; i < cnt.length; i++) {
// Consider the minimum
res += Math.min(cnt[i - 1], cnt[i]);
}
System.out.println(res - 1);
}
// Driver code
public static void main(String[] args)
{
// Given arr[]
int[] A = { 1, 1, 0, 0, 1, 0 };
// Function Call
countSubarrays(A);
}
}
// This code is contributed by 29AjayKumar
Python3
# Python3 program for the above approach
# Function to count subarrays
# having equal count of 0s and 1s
# with all 0s and all 1s grouped together
def countSubarrays(A):
# Stores the count
res = 0
# Initialize cur with first element
curr, cnt = A[0], [1]
for c in A[1:]:
# If the next element is same
# as the current element
if c == curr:
# Increment count
cnt[-1] += 1
else:
# Update curr
curr = c
cnt.append(1)
# Iterate over the array count
for i in range(1, len(cnt)):
# Consider the minimum
res += min(cnt[i - 1], cnt[i])
print(res - 1)
# Given arr[]
A = [1, 1, 0, 0, 1, 0]
# Function Call
countSubarrays(A)
C#
// C# program for the above approach
using System;
class GFG{
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
static void countSubarrays(int[] A)
{
// Stores the count
int res = 0;
// Initialize cur with first element
int curr = A[0];
int[] cnt = new int[A.Length];
cnt[0] = 1;
for(int c = 1; c < A.Length; c++)
{
// If the next element is same
// as the current element
if (A == curr)
// Increment count
cnt++;
else
// Update curr
curr = A;
cnt = 1;
}
// Iterate over the array count
for(int i = 1; i < cnt.Length; i++)
{
// Consider the minimum
res += Math.Min(cnt[i - 1], cnt[i]);
}
Console.WriteLine(res - 1);
}
// Driver code
public static void Main(String[] args)
{
// Given []arr
int[] A = { 1, 1, 0, 0, 1, 0 };
// Function Call
countSubarrays(A);
}
}
// This code is contributed by Amit Katiyar
Javascript
4
时间复杂度: O(N 2 )
辅助空间: O(1)
高效的方法:要优化上述方法,请按照以下步骤操作:
- 初始化一个变量,比如res ,以存储子数组的计数。
- 用数组的第一个值和数组cnt[]初始化一个变量,比如curr ,以跟踪连续的元素。
- 遍历数组并执行以下步骤:
- 如果当前元素等于curr ,则增加cnt[]的最后一个值。
- 否则,将curr更新为当前元素并将1附加到数组cnt[] 。
- 遍历数组cnt[]并找到相邻元素的最小值之和并将其添加到变量res 中。这确保了元素的频率相等。
- 完成上述步骤后,将res的值打印为子数组的结果计数。
下面是上述方法的实现:
C++
// C++ program for the above approach
#include
using namespace std;
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
void countSubarrays(int A[], int N)
{
// Stores the count
int res = 0;
// Initialize cur with first element
int curr = A[0];
vector cnt = {1};
for (int c = 1; c < N; c++)
{
// If the next element is same
// as the current element
if (A == curr)
// Increment count
cnt[cnt.size() - 1]++;
else
// Update curr
curr = A;
cnt.push_back(1);
}
// Iterate over the array count
for (int i = 1; i < cnt.size(); i++)
{
// Consider the minimum
res += min(cnt[i - 1], cnt[i]);
}
cout << (res - 1);
}
// Driver code
int main()
{
// Given arr[]
int A[] = { 1, 1, 0, 0, 1, 0 };
int N = sizeof(A) / sizeof(A[0]);
// Function Call
countSubarrays(A, N);
return 0;
}
// This code is contributed by divyesh072019
Java
import java.util.Vector;
// Java program for the above approach
class GFG {
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
static void countSubarrays(int[] A)
{
// Stores the count
int res = 0;
// Initialize cur with first element
int curr = A[0];
int[] cnt = new int[A.length];
cnt[0] = 1;
for (int c = 1; c < A.length; c++) {
// If the next element is same
// as the current element
if (A == curr)
// Increment count
cnt++;
else
// Update curr
curr = A;
cnt = 1;
}
// Iterate over the array count
for (int i = 1; i < cnt.length; i++) {
// Consider the minimum
res += Math.min(cnt[i - 1], cnt[i]);
}
System.out.println(res - 1);
}
// Driver code
public static void main(String[] args)
{
// Given arr[]
int[] A = { 1, 1, 0, 0, 1, 0 };
// Function Call
countSubarrays(A);
}
}
// This code is contributed by 29AjayKumar
蟒蛇3
# Python3 program for the above approach
# Function to count subarrays
# having equal count of 0s and 1s
# with all 0s and all 1s grouped together
def countSubarrays(A):
# Stores the count
res = 0
# Initialize cur with first element
curr, cnt = A[0], [1]
for c in A[1:]:
# If the next element is same
# as the current element
if c == curr:
# Increment count
cnt[-1] += 1
else:
# Update curr
curr = c
cnt.append(1)
# Iterate over the array count
for i in range(1, len(cnt)):
# Consider the minimum
res += min(cnt[i - 1], cnt[i])
print(res - 1)
# Given arr[]
A = [1, 1, 0, 0, 1, 0]
# Function Call
countSubarrays(A)
C#
// C# program for the above approach
using System;
class GFG{
// Function to count subarrays
// having equal count of 0s and 1s
// with all 0s and all 1s grouped together
static void countSubarrays(int[] A)
{
// Stores the count
int res = 0;
// Initialize cur with first element
int curr = A[0];
int[] cnt = new int[A.Length];
cnt[0] = 1;
for(int c = 1; c < A.Length; c++)
{
// If the next element is same
// as the current element
if (A == curr)
// Increment count
cnt++;
else
// Update curr
curr = A;
cnt = 1;
}
// Iterate over the array count
for(int i = 1; i < cnt.Length; i++)
{
// Consider the minimum
res += Math.Min(cnt[i - 1], cnt[i]);
}
Console.WriteLine(res - 1);
}
// Driver code
public static void Main(String[] args)
{
// Given []arr
int[] A = { 1, 1, 0, 0, 1, 0 };
// Function Call
countSubarrays(A);
}
}
// This code is contributed by Amit Katiyar
Javascript
4
时间复杂度: O(N)
辅助空间: O(N)
如果您希望与专家一起参加现场课程,请参阅DSA 现场工作专业课程和学生竞争性编程现场课程。